Location assisted service capability monitoring

ABSTRACT

A digitally stored map can indicate the signal quality for each of the map&#39;s regions. A device can determine its location, speed, and direction using global positioning system (GPS) and other sensors. Based on this information, the mobile device can predict a field of locations within which the device will probably be located within a specified future time frame. Based on both the information indicating signal quality and the probable future field of locations, the device can estimate a moment at which the device will probably begin to suffer from low-quality or absent signal. Using this prediction, the device can proactively perform a variety of anticipatory remedial actions. For example, the device can begin allocating a greater portion of currently available wireless network communication bandwidth to the reception of data packets that represent content that is being streamed to the device, so that the device can proactively buffer those packets.

BACKGROUND

The present disclosure relates generally to mobile communications, andin particular to techniques for adapting, during travel, to environmentsthat have weak or no mobile communication network access.

Computers and other electronic devices can communicate with each otherover networks such as local area networks, wide area networks, and theInternet. Mobile devices such as cell phones, including so-called smartphones, can communicate with each other wirelessly over a variety ofwireless networks including 3G and 4G networks. Smart phones can senddata packets over such networks, and through the Internet, to variousservers, and can receive information from such servers through similarchannels. In this manner, a user of a smart phone can view web pages,listen to music, and watch videos obtained from a remote server whilethat user is traveling. A smart phone can also send, to other smartphones, data packets that represent audio or textual communications.These data packets, traveling through the networks, contain fragments ofaudible or textual conversations between the users of the smart phones.However, typically, a mobile device can only send and receive datapackets while that mobile device has access to a wireless network.

As a user of a mobile device travels from one area to another, the usermay encounter locations in which access to a wireless network is limitedor non-existent. This may occur, for example, when the user has travelednearly or entirely out of range of a signal tower or wireless accesspoint. Until the mobile device comes back within range of the same oranother signal tower or wireless access point, the mobile device may beunable to conduct any communications with the external world. If amobile device user is involved in an important conversation or using animportant network-based service at the time that the user enters into azone in which signal strength is weak or absent, then the user maybecome frustrated at unexpectedly having his important activityinterrupted for some period of time.

SUMMARY

Certain embodiments of the invention can make use of information thatspecifies network communication signal strength or quality in variousgeographical regions. For example, a digitally stored map can indicate,for each region on the map, the network communication signal strength orquality within that region. A mobile device can determine its presentlocation using a device-internal mechanism such as global positioningsystem (GPS). Using built-in sensors such as a GPS, compass,accelerometer, gyroscope, and barometer, a mobile device also candetermine its present speed and direction of travel. Based on thislocation, speed, and direction information, the mobile device canpredict a field of geographical locations within which the mobile devicewill probably be located within a specified future time frame. Based onboth the information indicating geographical network communicationsignal quality and the probable future field of geographical locations,the mobile device can estimate a moment in the future at which themobile device will probably begin to suffer from low-quality or absentnetwork communication signal. Using this prediction, the mobile devicecan proactively perform a variety of anticipatory remedial actions.

For example, in response to determining that the mobile device is likelyto enter a communication “dead zone” within ten minutes, the mobiledevice can begin allocating a greater portion of currently availablewireless network communication bandwidth to the reception of datapackets that represent music or video that is currently being streamedto or downloaded to the mobile device, so that the mobile device canproactively buffer those data packets. The mobile device can thencontinue to play the music or video from the buffered data packets evenafter the mobile device has entered the communication dead zone. Foranother example, in response to making such a determination, the mobiledevice can alert the user, prior to the user's entry into thecommunication dead zone, that the path on which the user is travelingwill lead the user into a communication dead zone within a specifiedamount of time, so that the user can stop, change course, or take otheraction.

The techniques described herein can be used in a variety of travelscenarios. The particular means of transportation do not necessarilylimit application of the techniques described herein. For example,techniques described herein can be used regardless of whether the userof the mobile device is traveling in an automobile, a train pulled by alocomotive, an aircraft, or a watercraft.

The following detailed description together with the accompanyingdrawings will provide a better understanding of the nature andadvantages of the present invention.

BRIEF DESCRIPTION

FIG. 1 is a block diagram of a computer system according to anembodiment of the present invention.

FIG. 2 is a flow diagram illustrating an example technique forresponding to anticipated travel into a low-quality networkcommunication service region based on a mobile device's sensormeasurements, according to an embodiment of the invention.

FIG. 3 is a flow diagram illustrating an example technique forresponding to anticipated travel into a low-quality networkcommunication service region based on a route that the mobile device hasautomatically charted, according to an embodiment of the invention.

FIG. 4 is a flow diagram illustrating an example technique forresponding to anticipated travel into a low-quality networkcommunication service region based on downloaded map data, according toan embodiment of the invention.

FIG. 5 is a flow diagram illustrating an example technique for selectingan approach for determining that a mobile device is going to travel intoa low-quality network communication service region, according to anembodiment of the invention.

FIG. 6 is a flow diagram illustrating an example technique forinstructing applications to more aggressively cache streaming data basedon an amount of time that a mobile device is going to be travelingthrough a low-quality network communication service region, according toan embodiment of the invention.

FIG. 7 is a flow diagram illustrating an example technique forinstructing applications to more aggressively cache streaming data basedon wireless carrier-specific map data used to detect a mobile device'santicipated travel through a low-quality network communication serviceregion, according to an embodiment of the invention.

FIG. 8 is a flow diagram illustrating an example technique forinstructing applications to more aggressively cache streaming data basedon time-and-day-specific map data used to detect a mobile device'santicipated travel through a low-quality network communication serviceregion, according to an embodiment of the invention.

FIG. 9 is a flow diagram illustrating an example technique forinstructing applications executing on devices wirelessly tethered to amobile device to more aggressively cache streaming data in response to amobile device's anticipated travel through a low-quality networkcommunication service region, according to an embodiment of theinvention.

FIG. 10 is a flow diagram illustrating an example technique fordetecting a mobile device's anticipated travel through a low-qualitynetwork communication service region based on a field of potentiallocations, according to an embodiment of the invention.

FIG. 11 is a flow diagram illustrating an example technique forobtaining relevant map information regarding network communicationsignal qualities within regions through which a mobile device is likelyto travel, according to an embodiment of the invention.

FIG. 12 is a flow diagram illustrating an example technique forgenerating a network communication signal quality map based on signalquality measurements uploaded from various mobile devices, according toan embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a computing system 100 according to an embodiment ofthe present invention. Computing system 100 can be implemented as any ofvarious computing devices, including, e.g., a desktop or laptopcomputer, tablet computer, smart phone, personal data assistant (PDA),or any other type of computing device, not limited to any particularform factor. Computing system 100 can include processing unit(s) 105,storage subsystem 110, input devices 120, display 125, network interface135, and bus 140. Computing system 100 can be an iPhone or an iPad.

Processing unit(s) 105 can include a single processor, which can haveone or more cores, or multiple processors. In some embodiments,processing unit(s) 105 can include a general-purpose primary processoras well as one or more special-purpose co-processors such as graphicsprocessors, digital signal processors, or the like. In some embodiments,some or all processing units 105 can be implemented using customizedcircuits, such as application specific integrated circuits (ASICs) orfield programmable gate arrays (FPGAs). In some embodiments, suchintegrated circuits execute instructions that are stored on the circuititself. In other embodiments, processing unit(s) 105 can executeinstructions stored in storage subsystem 110.

Storage subsystem 110 can include various memory units such as a systemmemory, a read-only memory (ROM), and a permanent storage device. TheROM can store static data and instructions that are needed by processingunit(s) 105 and other modules of computing system 100. The permanentstorage device can be a read-and-write memory device. This permanentstorage device can be a non-volatile memory unit that storesinstructions and data even when computing system 100 is powered down.Some embodiments of the invention can use a mass-storage device (such asa magnetic or optical disk or flash memory) as a permanent storagedevice. Other embodiments can use a removable storage device (e.g., afloppy disk, a flash drive) as a permanent storage device. The systemmemory can be a read-and-write memory device or a volatileread-and-write memory, such as dynamic random access memory. The systemmemory can store some or all of the instructions and data that theprocessor needs at runtime.

Storage subsystem 110 can include any combination of computer readablestorage media including semiconductor memory chips of various types(DRAM, SRAM, SDRAM, flash memory, programmable read-only memory) and soon. Magnetic and/or optical disks can also be used. In some embodiments,storage subsystem 110 can include removable storage media that can bereadable and/or writeable; examples of such media include compact disc(CD), read-only digital versatile disc (e.g., DVD-ROM, dual-layerDVD-ROM), read-only and recordable Blu-Ray® disks, ultra density opticaldisks, flash memory cards (e.g., SD cards, mini-SD cards, micro-SDcards, etc.), magnetic “floppy” disks, and so on. The computer readablestorage media do not include carrier waves and transitory electronicsignals passing wirelessly or over wired connections.

In some embodiments, storage subsystem 110 can store one or moresoftware programs to be executed by processing unit(s) 105. “Software”refers generally to sequences of instructions that, when executed byprocessing unit(s) 105 cause computing system 100 to perform variousoperations, thus defining one or more specific machine implementationsthat execute and perform the operations of the software programs. Theinstructions can be stored as firmware residing in read-only memoryand/or applications stored in magnetic storage that can be read intomemory for processing by a processor. Software can be implemented as asingle program or a collection of separate programs or program modulesthat interact as desired. Programs and/or data can be stored innon-volatile storage and copied in whole or in part to volatile workingmemory during program execution. From storage subsystem 110, processingunit(s) 105 can retrieves program instructions to execute and data toprocess in order to execute various operations described herein.

A user interface can be provided by one or more user input devices 120,display device 125, and/or and one or more other user output devices(not shown). Input devices 120 can include any device via which a usercan provide signals to computing system 100; computing system 100 caninterpret the signals as indicative of particular user requests orinformation. In various embodiments, input devices 120 can include anyor all of a keyboard, touch pad, touch screen, mouse or other pointingdevice, scroll wheel, click wheel, dial, button, switch, keypad,microphone, and so on.

Display 125 can display images generated by computing system 100 and caninclude various image generation technologies, e.g., a cathode ray tube(CRT), liquid crystal display (LCD), light-emitting diode (LED)including organic light-emitting diodes (OLED), projection system, orthe like, together with supporting electronics (e.g., digital-to-analogor analog-to-digital converters, signal processors, or the like). Someembodiments can include a device such as a touchscreen that function asboth input and output device. In some embodiments, other user outputdevices can be provided in addition to or instead of display 125.Examples include indicator lights, speakers, tactile “display” devices,printers, and so on.

In some embodiments, the user interface can provide a graphical userinterface, in which visible image elements in certain areas of display125 are defined as active elements or control elements that the user canselect using user input devices 120. For example, the user canmanipulate a user input device to position an on-screen cursor orpointer over the control element, then click a button to indicate theselection. Alternatively, the user can touch the control element (e.g.,with a finger or stylus) on a touchscreen device. In some embodiments,the user can speak one or more words associated with the control element(the word can be, e.g., a label on the element or a function associatedwith the element). In some embodiments, user gestures on atouch-sensitive device can be recognized and interpreted as inputcommands; these gestures can be but need not be associated with anyparticular array in display 125. Other user interfaces can also beimplemented.

Network interface 135 can provide voice and/or data communicationcapability for computing system 100. In some embodiments, networkinterface 135 can include radio frequency (RF) transceiver componentsfor accessing wireless voice and/or data networks (e.g., using cellulartelephone technology, advanced data network technology such as 3G, 4G orEDGE, WiFi (IEEE 802.11 family standards, or other mobile communicationtechnologies, or any combination thereof), GPS receiver components,and/or other components. In some embodiments, network interface 135 canprovide wired network connectivity (e.g., Ethernet) in addition to orinstead of a wireless interface. Network interface 135 can beimplemented using a combination of hardware (e.g., antennas,modulators/demodulators, encoders/decoders, and other analog and/ordigital signal processing circuits) and software components.

Bus 140 can include various system, peripheral, and chipset buses thatcommunicatively connect the numerous internal devices of computingsystem 100. For example, bus 140 can communicatively couple processingunit(s) 105 with storage subsystem 110. Bus 140 also connects to inputdevices 120 and display 125. Bus 140 also couples computing system 100to a network through network interface 135. In this manner, computingsystem 100 can be a part of a network of multiple computer systems(e.g., a local area network (LAN), a wide area network (WAN), anIntranet, or a network of networks, such as the Internet. Any or allcomponents of computing system 100 can be used in conjunction with theinvention.

Some embodiments include electronic components, such as microprocessors,storage and memory that store computer program instructions in acomputer readable storage medium. Many of the features described in thisspecification can be implemented as processes that are specified as aset of program instructions encoded on a computer readable storagemedium. When these program instructions are executed by one or moreprocessing units, they cause the processing unit(s) to perform variousoperation indicated in the program instructions. Examples of programinstructions or computer code include machine code, such as is producedby a compiler, and files including higher-level code that are executedby a computer, an electronic component, or a microprocessor using aninterpreter.

Through suitable programming, processing unit(s) 105 can provide variousfunctionality for computing system 100. For example, processing unit(s)105 can execute a network communication signal quality mappingapplication. In some embodiments, the network communication signalquality mapping application is a software-based process that can respondto imminent entry of computing system 100 into a region havinglow-quality or absent network communication availability by sendingadvisory notifications to other applications that have registered withthe network communication signal quality mapping application.

It will be appreciated that computing system 100 is illustrative andthat variations and modifications are possible. Computing system 100 canhave other capabilities not specifically described here (e.g., mobilephone, global positioning system (GPS), power management, one or morecameras, various connection ports for connecting external devices oraccessories, etc.). Further, while computing system 100 is describedwith reference to particular blocks, it is to be understood that theseblocks are defined for convenience of description and are not intendedto imply a particular physical arrangement of component parts. Further,the blocks need not correspond to physically distinct components. Blockscan be configured to perform various operations, e.g., by programming aprocessor or providing appropriate control circuitry, and various blocksmight or might not be reconfigurable depending on how the initialconfiguration is obtained. Embodiments of the present invention can berealized in a variety of apparatus including electronic devicesimplemented using any combination of circuitry and software.

Travel-Anticipatory Data Pre-Caching

According to an embodiment of the invention, a mobile device candetermine, based on both (a) geographical network communication signalquality information and (b) speed and heading information, that themobile device might possibly enter a low-quality signal zone within aspecified period of time in the future. In response to thisdetermination, the mobile device can invoke a particular operatingsystem feature. The invocation of the particular operating systemfeature can cause the operating system of the mobile device to instructapplications currently executing on the mobile device to beginpre-caching the data that those applications will require, or, more ofthe data that those applications are currently receiving via wirelesscommunication networks. Applications can be designed to respond to suchan operating system instruction by requesting more data from their datasources, and/or by consuming a greater portion of the mobile device'sbandwidth in order to obtain such data. As used herein, the phrase“signal quality” can include, but is not limited to, the signal strengthand noise levels of the mobile device's wireless transmission, the biterror rate of the encoded data on the channel, and the application-levelthroughput.

For example, in response to determining that the mobile device willenter a network communication signal “dead zone” within a specifiedthreshold amount of time, the mobile device's operating system caninstruct a music-streaming-and-playing application, such as Pandora, tobegin to utilize an increased portion of the mobile device's networkcommunication bandwidth to download and buffer data packets that containinformation representing the music. In response, themusic-streaming-and-playing application can download and buffer thesedata packets in greater quantities prior to the mobile device's entryinto the network communication signal dead zone. Thereafter, while themobile device is traveling through the network communication signal deadzone, the mobile device can continue to play music to its using thepreviously buffered information even though the mobile device currentlycannot receive any network communication signal and even though themobile device currently cannot receive any data packets wirelessly. Forexample, a particular movie-streaming application executing on a mobiledevice might normally buffer up to 5 minutes worth of content to playback to a user before temporarily ceasing to request more of thatcontent over a wireless communication network. However, in response toan alert that the mobile device will be entering a network communicationdead zone within a threshold amount of time from the present, theapplication can begin to buffer 10 minutes worth of content instead. Asused herein, the phrase “dead zone” means a geographical area in whichthe mobile device cannot transmit or receive data wirelessly due to theabsence of a signal transmitter/receiver within wireless communicationrange of the mobile device.

In an embodiment of the invention, the amount of increase in thequantity of data that an application buffers in response to detectingimminent entry into a region of poor network communication servicequality can be based on a quantity of time that the mobile device onwhich the application executes is predicted to remain within thatregion. This predicted amount of time can be based on the size of theregion, the speed and direction of the mobile device, and/or a knownroute that the mobile device is predicted to follow through that region.In an embodiment of the invention, an application pre-caches asufficient quantity of data prior to entry into the poor signal qualityregion to enable the application to continue to play content at a normalrate (without acquiring any further data) during the entire interval oftime that the mobile device is predicted to remain within the poorsignal quality region.

FIG. 2 is a flow diagram illustrating an example technique 200 forresponding to anticipated travel into a low-quality networkcommunication service region based on a mobile device's sensormeasurements, according to an embodiment of the invention. In block 202,the mobile device can use its sensors to determine the mobile device'scurrent location. In block 204, the mobile device can use its sensors todetermine the mobile device's current direction of travel. In block 206,the mobile device can use its sensors to determine the mobile device'scurrent speed of travel. In block 208, based at least in part on themobile device's current location, the mobile device's current directionof travel, and the mobile device's current speed of travel, the mobiledevice can determine that it will enter the region within a specifiedthreshold amount of time. In block 210, in response to detecting thatthe mobile device will enter the region within the specified thresholdamount of time, the mobile device can automatically present, on itsdisplay, a notification alerting the mobile device's user that themobile device is going to enter the region.

FIG. 3 is a flow diagram illustrating an example technique 300 forresponding to anticipated travel into a low-quality networkcommunication service region based on a route that the mobile device hasautomatically charted, according to an embodiment of the invention. Inblock 302, the mobile device can automatically determine a route alongmap-specified paths In block 304, the mobile device can determine thatthe route passes through the region. In block 306, in response todetermining that the route passes through the region, the mobile devicecan automatically present, on its display, a notification alerting themobile device's user that the mobile device is going to enter theregion.

FIG. 4 is a flow diagram illustrating an example technique 400 forresponding to anticipated travel into a low-quality networkcommunication service region based on downloaded map data, according toan embodiment of the invention. In block 402, the mobile device canreceive map data that indicates, for each particular region designatedwithin the map data, a wireless network communication service signalquality existing within that particular region. In block 404, the mobiledevice can determine that it is traveling on a course that will take itinto a region for which the map data indicates a wireless networkcommunication service signal quality that is less than a specified levelof quality. In block 406, in response to detecting that the mobiledevice is traveling toward the region, the mobile device canautomatically present, on its display, a notification alerting themobile device's user that the mobile device is going to enter theregion.

FIG. 6 is a flow diagram illustrating an example technique 600 forinstructing applications to more aggressively cache streaming data basedon an amount of time that a mobile device is going to be travelingthrough a low-quality network communication service region, according toan embodiment of the invention. In block 602, the mobile device candetermine that it is going to enter a region having a wireless networkcommunication service signal quality that is less than a specifiedthreshold. In block 604, the mobile device can determine an amount oftime that it is going to be traveling within the region. In block 606,the mobile device can instruct applications to begin caching wirelesslystreamed data at a rate that enables the applications to pre-cache aquantity of data sufficient to permit the applications to continuepresenting content, throughout the mobile device's presence within theregion, at a rate at least as fast as a rate at which the applicationshad been presenting the content prior to the mobile device's entry intothe region.

Field of Potential Future Locations

In one embodiment of the invention, based on the mobile device's currentlocation, speed, and direction, the mobile device can estimate a linearpath that the mobile device is likely to follow. In response todetermining that the path intersects a known region of poor or absentnetwork communication signal quality, the mobile device can initiatedata pre-caching in the manner discussed above. Additionally oralternatively, in one embodiment of the invention, at any given moment,the mobile device can calculate a field of potential future locations inwhich the mobile device could be present within a specified timeinterval following the present moment assuming that the mobile device'sspeed remained constant but that the mobile device's direction wassubject to change during that time interval. In response to determiningthat this field of potential future locations intersects a known regionof poor or absent network communication signal quality, the mobiledevice can initiate data pre-caching in the manner discussed above. Insuch an embodiment, as the mobile device's speed and location changes,the field of potential future locations can change accordingly. In oneembodiment of the invention, a learning algorithm can adapt to changesin the speed at which the mobile device travels over time in order tofurther refine the accuracy of the field of potential future locationsdiscussed above.

In one embodiment of the invention, the mobile device can refine thefield of potential future locations discussed above based at least inpart on information that indicates a type of environment in which themobile device is currently located. This environment type can bespecified within digitally stored map information, for example. The mapinformation may indicate, for each region, a type of environment thatexists within that region. For example, one region might contain a“city” environment type, while another region might contain an “openspace” environment type. The narrowness of the field can be adjustedbased on the environment type of the region in which the mobile deviceis currently located. For example, if the mobile device is currentlylocated within a “city” environment type, then the mobile device cananticipate a field of potential future locations that more narrowlyadheres to the mobile device's current linear trajectory than the mobiledevice would anticipate if the mobile device were currently locatedwithin an “open space” environment type.

In one embodiment of the invention, the mobile device can estimate alikelihood of change of direction based on the mobile device's currentspeed in order to calculate the field of potential future locations. Forexample, if the mobile device's current speed is relatively slow, thenthe mobile device can responsively estimate a relatively high likelihoodthat the mobile device's direction of travel may change, and constructthe field of potential future locations accordingly; such a field ofpotential future locations might encompass regions in a relatively widevariety of directions about the mobile device's current direction, butat a relatively limited distance from the mobile device's currentlocation. For another example, if the mobile device's current speed isrelatively high, then the mobile device can responsively estimate arelatively low likelihood that the mobile device's direction of travelmay change, and construct the field of potential future locationsaccordingly; such a field of potential future locations might encompassregions in a relatively narrow variety of directions about the mobiledevice's current direction, but at a relatively greater distance fromthe mobile device's current location. In one embodiment of theinvention, the mobile device can receive user input that indicates amode of transportation, and the mobile device can construct the field ofpotential future locations in a manner that takes this mode intoaccount. For example, if the user input indicates that the mode oftransportation is by train, then the mobile device can estimate themobile device's potential future locations with a fairly highlikelihood, due to the path of the rails being fixed and due to thetrain's speeds being relatively predetermined along its route.

In one embodiment of the invention, data obtained from the mobiledevice's sensors, potentially including the device's accelerometer,gyroscope, and barometer, can be used to estimate a context of travel.For example, using such data, the mobile device may estimate that themobile device's user is currently walking, or jogging, or running, orbicycling, or driving, or flying. In one embodiment of the invention,the mobile device can construct the field of potential future locationsbased at least in part on the mobile device's current context of travel.For example, if the mobile device's current context of travel iswalking, then the mobile device can responsively construct the field ofpotential future locations accordingly; such a field of potential futurelocations might encompass regions in a relatively wide variety ofdirections about the mobile device's current direction, but at arelatively limited distance from the mobile device's current location.For another example, if the mobile device's current context of travel isdriving, then the mobile device can responsively construct the field ofpotential future locations accordingly; such a field of potential futurelocations might encompass regions in a relatively narrow variety ofdirections about the mobile device's current direction, but at arelatively greater distance from the mobile device's current location.

FIG. 10 is a flow diagram illustrating an example technique 1000 fordetecting a mobile device's anticipated travel through a low-qualitynetwork communication service region based on a field of potentiallocations, according to an embodiment of the invention. In block 1002,based at least in part on (1) a current location of the mobile device,(2) a current speed of the mobile device, and (3) a current direction ofthe mobile device, the mobile device can determine a field of potentiallocations in which the mobile device can potentially be located within aspecified interval of time following a current time. In block 1004,based at least in part on (a) the field of potential locations and (b)digital map data that indicates wireless network communication servicesignal qualities for regions in a plurality of regions, the mobiledevice can determine that the field of potential locations at leastpartially overlaps a particular region in which a wireless networkcommunication service signal quality is less than a specified threshold.In block 1006, in response to determining that the field of potentiallocations at least partially overlaps a particular region in which awireless network communication service signal quality is less than aspecified threshold, the mobile device can send a notification to one ormore applications that have registered to receive notifications.

Obtaining Relevant Map Information

According to an embodiment of the invention, a mobile device canestimate an amount of time during which the mobile device is likely tobe in a geographical zone in which the mobile device will have either nowireless network access at all or access only to a network communicationsignal that is less than a specified threshold of quality or strength.In other words, in an embodiment of the invention, a mobile device canestimate how long it will be in a network communication signal dead zonesometime in the future.

In an embodiment of the invention, a navigation application executing onthe mobile device can automatically determine a route of travel from auser-specified origin to a user-specified destination. The route oftravel can follow one or more roads indicated on a map digitally storedwithin the mobile device. The map information digitally stored withinthe mobile device can specify, for each region of a plurality of regionsinto which the map is geographically divided, a network communicationsignal quality or strength that is known to exist within that region.Some regions might have greater signal qualities than other regionshave. The route of travel can pass through one or more of these regions.In one embodiment of the invention, each region can be a square area onthe map. In an alternative embodiment of the invention, each region canbe a hexagonal area on the map.

In an embodiment of the invention, after the mobile device hasdetermined the route along which it is probably going to travel, asdescribed above, the mobile device can determine the set of regions, ormap tiles, through which the route passes. The mobile device can thenproactively and wirelessly download the signal quality or strengthinformation for these particular regions, or for these particular maptiles, while the mobile device is still within a region in which thenetwork communication signal quality is sufficiently high. The mobiledevice can then use this proactively obtained signal quality informationfor various purposes, such as for the data pre-caching purpose discussedabove. In this manner, the mobile device ensures that it has signalquality information at least for the regions that are likely to berelevant, due to the mobile device's anticipated future travel throughthose regions.

As is discussed above, in an embodiment of the invention, a mobiledevice can determine a route along which that mobile device is predictedto travel. In such an embodiment, the route can be used to estimatetimes of entry into, and times of travel through, regions characterizedby low-quality or absent network communication service availability.However, in alternative embodiments of the invention, other indicia ofpaths of travel can be used by the mobile device for similar purposes.For example, in one embodiment of the invention, a mobile device canexecute a “passbook” type of application that stores digital boardingpass information and potentially other kinds of travel-relatedinformation for use during a user's transportation. In such anembodiment of the invention, the mobile device can observe the departuredate and time, the origin of departure, the arrival date and time, andthe destination of arrival associated with a digital boarding pass orother digital travel document stored within the passbook. Based on thisobserved information from the passbook, the mobile device can anticipatea potential path through various regions of a signal quality map atspecific times and dates. Using this potential path information, themobile device can initiate pre-caching, partial map downloading, orother anticipatory actions in advance of the mobile device's predictedentry into a region characterized by low-quality or absent networkcommunication service availability. Virtually any source of dataaccessible by the mobile device and indicative of a travel context canbe used by the mobile device to predict a future course of travel and toperform compensatory operations accordingly.

FIG. 11 is a flow diagram illustrating an example technique 1100 forobtaining relevant map information regarding network communicationsignal qualities within regions through which a mobile device is likelyto travel, according to an embodiment of the invention. In block 1102,the mobile device can detect that it is traveling along a particularpath. In block 1104, in response to detecting that it is traveling alongthe particular path, the mobile device can determine regions of a mapthat are intersected by the particular path. In block 1106, the mobiledevice can wirelessly download, from a server, a set of map tiles thatcorrespond to the regions that are intersected by the particular path.The set of downloaded map tiles can exclude all map tiles that do notcorrespond to the regions that are intersected by the particular path.The map tiles can specify qualities of network communication signalswithin regions to which those map tiles correspond.

Dual Techniques for Anticipating Dead Zones

In an embodiment of the invention, in response to determining that theroute passes through one or more regions in which the networkcommunication signal quality is less than a specified threshold level ofquality, the mobile device can automatically instruct applicationsexecuting on the device to begin pre-caching data packets in the mannerdiscussed above. The mobile device can issue this instruction even ifthe mobile device is not currently in motion, and even if the mobiledevice has not yet left its point of origin. Because the mobile deviceis apprised of its probable future passage through one or more networkcommunication signal dead zones due to the passage of the route throughregions including those dead zones, the mobile device can begin to causedata packet pre-caching for content streaming and downloadingapplications to begin regardless of the mobile device's currentlocation, speed, or direction.

In an embodiment of the invention, the mobile device uses the routeinformation discussed above in conjunction with the current location,speed, and direction information that the mobile device automaticallydetermines using its sensors in order to determine whether and when toinstruct content streaming and downloading applications to beginpre-caching data packets prior to entry into network communicationsignal dead zones. Each of these items of information can be a separateinput into an algorithm or function that the mobile device uses todetermine whether and when to instruct content streaming and downloadingapplications executing on the device to begin pre-caching data packets.

In one embodiment of the invention, if the mobile device is aware of aprobable route of future travel due to a user's activation of anautomatic route-determining mechanism, such as those found withinautomobile navigation applications, then the mobile device can use thatroute information along with the digital signal quality map in order todetermine whether and when to instruct content streaming and downloadingapplications to begin pre-caching data packets. In such an embodiment ofthe invention, if the mobile device is unaware of such a probable route,potentially because the user has not activated an automaticroute-determining mechanism, then the mobile device can alternativelyuse the current location, speed, and direction information determinedusing the mobile device's sensors in order to determine whether and whento instruct content streaming and downloading applications to beginpre-caching data packets.

FIG. 5 is a flow diagram illustrating an example technique 500 forselecting an approach for determining that a mobile device is going totravel into a low-quality network communication service region,according to an embodiment of the invention. In block 502, the mobiledevice can determine whether any data stored on the mobile deviceindicates a route that the mobile device will follow in the future. Inblock 504, in response to determining that no data stored on the mobiledevice indicates a route that the mobile device will follow in thefuture, the mobile device can use its sensors to determine its location,speed, and direction. In block 506, based at least in part on thesensor-determined location, speed, and direction, the mobile device candetermine that it will enter the region within a specified thresholdamount of time. In block 508, in response to detecting that the mobiledevice will enter the region within the specified threshold amount oftime, the mobile device can automatically present, on its display, anotification alerting the mobile device's user that the mobile device isgoing to enter the region.

Building Map Data Through Crowd-Sourcing

According to an embodiment of the invention, a crowd-sourcing techniquecan be used in order to build the network communication signal qualitymap data discussed above. In such an embodiment, actual experientialdata transmitted from multiple separate mobile devices can be used toconstruct the map data. For example, as each mobile device in a set ofmany mobile devices travels through various regions located on a map,that mobile device can measure the network communication signal qualityor strength that it experiences within those regions. Each such mobiledevice can then upload, to a remote server, information that specifiesthe device-experienced signal quality or strength for the regions inwhich that mobile device actually conducted measurements. For example, amobile device can upload, to the remote server, information indicatingthat while the mobile device was located in a particular region, themobile device experienced a particular bandwidth in its wireless datatransmissions, and/or the mobile device detected a wireless signalhaving a strength or quality measured by a particular quantity of“bars.” The remote server can accumulate and aggregate this information,using the measurements from multiple separate mobile devices to populatenetwork communication signal quality measurements for various regionswithin the map data. Other mobiles devices, as well as the mobiledevices that uploaded some of the measurements to the remote server, canthen obtain the map data, at least partially populated using thecrowd-sourcing techniques described above, from the remote server. Forexample, the mobile devices can periodically download the map data, orrelevant portions thereof, from the remote server over a wirelessnetwork.

In one embodiment of the invention, each mobile device in the set ofmobile devices can anonymize the signal quality measurements that itsends to the remote server prior to sending those measurements. Eachsuch mobile device can remove, from the measurements that it sends tothe remote server, all information that could be used to identify themobile device or the mobile device's user. In one embodiment of theinvention, each mobile device can send, to the remote server, only (a)the mobile device's geographical coordinates at the time of themeasurement and (b) the data indicating the measured signal quality orstrength at those coordinates. In other embodiments, each mobile devicecan send other potentially useful information to the remote server aswell, such as the time of day at which the signal quality was measured,the date on which the signal quality was measured, the kind of network(e.g., 3G, 4G, etc.) whose signal quality was measured, the carrier ofthe network (e.g., Verizon, AT&T, T-Mobile, etc.) whose signal qualitywas measured, etc. In an embodiment of the invention, a mobile devicecan first request and obtain, from its user, consent to share signalquality measurement data with the remote server and other mobile devicesbefore sending such measurement data to the remote server periodicallyor in response to specified event triggers.

In one embodiment of the invention, the remote server can enhance andupdate the signal quality information within the map information basedon the measurements received from various mobile devices, but also caninitially populate the map information with signal quality data obtainedfrom one or more cell phone carriers. For example, the remote server canobtain, from companies such as Verizon, AT&T, T-Mobile, etc.,information indicating the locations of the cell towers that serverthose companies' wireless communication networks. The remote server canobtain, from these carriers, measurements of the levels of signalquality and strength surrounding each tower. Alternatively, the remoteserver can estimate these measurements based simply on the locations ofthe cell towers and the distances of each map region from the regions inwhich the cell towers are located. The remote server can initiallypopulate the map information with these carrier-provided signal qualitymeasurements, which can be theoretical estimates based primarily onantenna location and direction. Then, as mobile devices begin to uploadtheir own measurements, the remote server can update the map informationbased on those measurements. In one embodiment of the invention, theremote server can maintain a separate network communication signalquality map for each of the carriers, because different carriers canhave cell towers located in different regions. In such an embodiment,the remote server can determine which carrier a particular mobile deviceuses in response to receiving signal quality measurement data from thatparticular mobile device, and then use that signal quality measurementdata to update the network communication signal quality map only forthat carrier, because the measurement data from the particular mobiledevice pertains only to that carrier's wireless communication networks.In an embodiment of the invention, each mobile device subscribing to aparticular carrier's network can initially download from the remoteserver and locally store, in its memory, the signal quality map datapertaining specifically to that particular carrier; such map data can beinitially populated by the remote server using signal qualitymeasurements from the particular carrier itself.

FIG. 12 is a flow diagram illustrating an example technique 1200 forgenerating a network communication signal quality map based on signalquality measurements uploaded from various mobile devices, according toan embodiment of the invention. In block 1202, a server can receive,from multiple mobile devices, measurements that indicate qualities ofnetwork communication signals within multiple regions. For example, theserver can receive (1) a first measurement pertaining to a particularregion from a first mobile device and (2) a second measurementpertaining to the particular region from a second mobile device that isseparate from the first mobile device. For another example, the servercan receive, from the same mobile device, (1) a first measurementpertaining to a first region, and (2) a second measurement pertaining toa second region that is separate from the first region.

In block 1204, based on the measurements, the server can update storedmap data that specifies, for each particular region, a quality of anetwork communication signal within that particular region. In block1206, the server can send, to each of the mobile devices (andpotentially others also), at least a portion of the stored map data thatwas updated in block 1204.

FIG. 7 is a flow diagram illustrating an example technique 700 forinstructing applications to more aggressively cache streaming data basedon wireless carrier-specific map data used to detect a mobile device'santicipated travel through a low-quality network communication serviceregion, according to an embodiment of the invention. In block 702, themobile device can select, from among a plurality of wireless networkcarriers, a particular wireless network carrier that is currently beingused by the mobile device. In block 704, the mobile device can select,from among a plurality of maps that are associated with differentwireless network carriers, a particular map that is associated with theparticular network carrier. In block 706, based at least in part onwireless network communication service signal qualities that areassociated with different regions of the particular map, the mobiledevice can determine that it is going to enter a region having awireless network communication service signal quality that is less thana specified threshold. In block 708, in response to determining that itis going to enter the region, the mobile device can instructapplications to begin, prior to the entry of the mobile device into theregion, caching wirelessly streamed data at a rate faster than a rate atwhich the one or more applications had been caching wirelessly streameddata.

In one embodiment of the invention, the remote server can maintain aseparate network communication signal quality map for each differentnetwork technology type (e.g., 2G, 3G, 4G, etc.), because differentnetwork technology types can have different wireless communicationsignal qualities within a particular region. In such an embodiment, theremote server can determine which network technology type (e.g., 2G, 3G,4G, etc.) a particular mobile device used in response to receivingsignal quality measurement data from that particular mobile device, andthen use that signal quality measurement data to update the networkcommunication signal quality map only for that particular networktechnology type, because the measurement data from the particular mobiledevice pertains only to that particular network technology type. In anembodiment of the invention, the remote server maintains and updates aseparate wireless network communication signal quality map for eachpossible permutation of wireless service carrier and wireless networktechnology type (e.g., Verizon 3G, AT&T 3G, Verizon 4G, AT&T 4G, etc.).

In one embodiment of the invention, the remote server can maintain aseparate network communication signal quality map for each differenttime-of-day and day-of-week combination, because network congestionmight be more severe during certain times-of-day and days-of-week thanat other times-of-day on other days-of-week. In such an embodiment, theremote server can determine the particular time-of-day and day-of-weekat which a particular mobile device made a signal quality measurement inresponse to receiving signal quality measurement data from thatparticular mobile device, and then use that signal quality measurementdata to update the network communication signal quality map only forthat particular time-of-day and day-of-week combination, because themeasurement data from the particular mobile device pertains only to thatparticular time-of-day and that particular day-of-week. In an embodimentof the invention, the remote server maintains and updates a separatewireless network communication signal quality map for each possiblepermutation of wireless service carrier, wireless network technologytype, and time-of-day/day-of-week combination. In such an embodiment,when attempting to determine whether a mobile device is soon likely toenter a region having limited or lacking network communication serviceavailability, as discussed above, that mobile device can download (e.g.,from the remote server) fresh map data specifically for the permutationthat is presently applicable to that mobile device's current situation(e.g., for the mobile device's current carrier, current networktechnology type, and the current time-of-day and day-of-week), and usethat situation-specific map data to make the determination.

FIG. 8 is a flow diagram illustrating an example technique 800 forinstructing applications to more aggressively cache streaming data basedon time-and-day-specific map data used to detect a mobile device'santicipated travel through a low-quality network communication serviceregion, according to an embodiment of the invention. In block 802, themobile device can select, from among a plurality of maps that areassociated with different time-of-day and day-of-week combinations, aparticular map that is associated with a current time-of-day and acurrent day-of-week. In block 804, based at least in part on wirelessnetwork communication service signal qualities that are associated withdifferent regions of the particular map, the mobile device can determinethat it is going to enter a region having a wireless networkcommunication service signal quality that is less than a specifiedthreshold. In block 806, in response to determining that it is going toenter the region, the mobile device can instruct applications to begin,prior to the entry of the mobile device into the region, cachingwirelessly streamed data at a rate faster than a rate at which the oneor more applications had been caching wirelessly streamed data.

As is mentioned above, in one embodiment of the invention, mobiledevices can report their geographical coordinates to the remote serveralong with network communication signal quality measurements pertainingto those coordinates. In one embodiment of the invention, these mobiledevices can use mechanisms other than GPS in order to determine thesecoordinates. For example, in one embodiment of the invention, mobiledevices can determine their locations using cell identifiers(IDs)—identifiers uniquely associated with the cell towers through whichthose mobile devices wirelessly access the network. For another example,in one embodiment of the invention, mobile devices can determine theirlocations based on WiFi Internet Protocol (IP) addresses of the WiFiaccess points through which those mobile devices wirelessly access thenetwork. Avoiding the use of GPS to determine a mobile device's currentcoordinates can help to preserve the mobile device's battery life.

Thus, in certain embodiments of the invention, crowd-sourced data can betransformed into a network communication service map. Using variousmeasurements from different fields, regional polygons specifying servicequalities in various regions of the map can be populated. Variousfilters can be applied to the measurements in populating the map.Various algorithms can be applied to generate the service quality levelsfor each regional polygon within the map. For example, in oneembodiment, a weight can be associated with each measurement based onhow recently that measurement was observed; more recently observedmeasurements can be weighted more heavily than less recently observedmeasurements. Each measurement can be multiplied by its associatedweight, and then the resulting weighted measurements can be averagedtogether to produce the service quality level for a particular regionalpolygon within the map. After the network communication service map hasbeen generated, the map can be obtained by mobile devices that arelocated within the field and used to anticipate and compensate forpotential entry into regions of low-quality or no service, such as byinstructing applications executing on those mobile devices to bufferextra data packets prior to such potential entry. In certain embodimentsof the invention, algorithms can be used to determine probable directionof travel so that mobile devices can wirelessly download, from theremote server, map tiles that indicate service qualities of the regionsthrough which the mobile devices are most likely to travel in the nearfuture. In an embodiment of the invention, an operating system executingon the mobile device provides a service to applications through whichthis buffering and downloading can be accomplished. The operatingsystem-provided service can be exposed to the application in the form ofone or more application programming interfaces (APIs).

Application Registration

According to an embodiment of the invention, certain applications thatexecute on a mobile device can register with the operating system thatis executing on that device to request crowd-sourcing and data bufferingservices offered by that operating system. For example, by registeringwith the operating system, a particular application can indicate to theoperating system that the particular application is a content-streamingapplication that is interested in receiving alerts that the particularapplication should buffer extra data packets in anticipation of poor orabsent network communication signals in the near future. In anembodiment of the invention, for each application that has registered inthis manner with the operating system, the operating system sends analert to that application in response to a module determining that themobile device will be entering a region having less than a specifiedquality of wireless network communication services within a specifiedthreshold amount of time. In one embodiment of the invention, fiveminutes prior to the moment in which the mobile device is predicted toenter a poor network communication service quality region, the operatingsystem can send a notification to each of the registered applicationsinstructing them to begin aggressive buffering. In one embodiment of theinvention, the operating system also can indicate, in the notification,a predicted amount of time that the mobile device is predicted to remainwithin that region, so that registered applications can pre-cache asufficient quantity of data to allow them to continue to present contentat a normal rate throughout the time that the mobile device is predictedto remain within that region.

Device Tethering

Some mobile devices, such as some smart phones, come equipped with thecapability of acting as a wireless network communication access point,or “hot spot,” for other nearby devices capable of communicatingwirelessly (e.g., via Bluetooth technology) with those mobile devices.In an embodiment of the invention, the mobile device to which otherdevices are tethered can send alerts to those tethered devices in thesame manner that the mobile device's own operating system can send suchalerts to registered applications that are executing on the mobiledevice itself. For example, applications executing on a tethered devicecan register with an operating system of a mobile device to which thattethered device is tethered in order to make use of the predictive alertservices offered by that mobile device. The mobile device's operatingsystem can send “impending dead zone entry” alerts to the registeredapplications executing on these tethered devices in a manner similar tothat in which the mobile device's operating system sends such alerts toregistered application executing locally on the mobile device itself.For example, registered applications can execute on a laptop computerthat is wirelessly tethered to a mobile device and is using the mobiledevice's wireless communication services. For another example,registered application can execute on a vehicle's built-in navigationsystem that is wirelessly tethered to a mobile device and is using themobile device's wireless communication services. The mobile device canprovide a registration system for applications executing on tethereddevices.

According to an embodiment of the invention, the mobile device'soperating system listens on a particular port for registration requestsfrom applications that can execute on the mobile device itself or onwirelessly tethered devices. In response to receiving these registrationrequests, the mobile device's operating system adds identifiers of theseapplications to a list of registered applications. Thereafter, wheneverthe mobile device's operating system determines that entry into anetwork communication signal dead zone is approaching, the mobiledevice's operating system can send out alerts or notifications on theparticular port. Registered applications executing on tethered devicesand on the mobile device itself can listen for such alerts ornotifications on the particular port, and can respond to those alerts ornotifications in application-customized manners (e.g., bufferingadditional data packets, notifying a user of the application, etc.). Inan embodiment of the invention, registration and notification can beconducted using Hypertext Transfer Protocol (HTTP) over InternetProtocol (IP). However, in alternative embodiments of the invention,different protocols can be used for these purposes.

FIG. 9 is a flow diagram illustrating an example technique 900 forinstructing applications executing on devices wirelessly tethered to amobile device to more aggressively cache streaming data in response to amobile device's anticipated travel through a low-quality networkcommunication service region, according to an embodiment of theinvention. In block 902, the mobile device can determine that it isgoing to enter a region having a wireless network communication servicesignal quality that is less than a specified threshold. In block 904, inresponse to determining that it is going to enter the region, the mobiledevice can determine a set of applications that are executing on devicesthat are wirelessly tethered to the mobile device. In block 906, themobile device can wirelessly transmit, to each application in the set ofapplications, a message instructing that application to begin cachingwirelessly streamed data at a rate faster than a rate at which thatapplication had been caching wirelessly streamed data.

Anticipatory Actions for Different Service Types

As is discussed above, in an embodiment of the invention, notificationsare provided to content-streaming applications in anticipation of theimpending entry of a mobile device into a region characterized by a lowquality of network communication service availability. However, invarious embodiments of the invention, such notifications may be providedto applications of a variety of different types, regardless of whetherthose applications are content-streaming applications. Other types ofapplications also can benefit from the notifications discussed above.For example, a text messaging application can register to receive suchnotifications. For another example, a telephony application can registerto receive such notifications. What each registered application does inresponse to receiving such a notification can depend on thatapplication's type.

For example, a “reminders” application executing on a mobile device suchas a smart phone can register to receive notifications about the mobiledevice's imminent entry into a region of poor quality communicationservices, including voice communication services as well as datacommunication services. In response to receiving a notification that themobile device will be entering such a region within five minutes and ispredicted to remain within that region for thirty minutes, the remindersapplication can search its list of scheduled reminders for remindersthat (a) will require communication services (such as reminders to maketelephone calls) and (b) are scheduled to occur during the interval oftime during which those communication services are predicted to belimited or lacking in availability. For each such reminder, thereminders application can take some pre-emptive action. For example, thereminders application can temporally move, to the present time, all suchscheduled reminders, so that those particular reminders triggerimmediately, while the mobile device can still access communicationservices, rather than at those reminders' regularly scheduled times,during which the mobile device likely will not be able to accesscommunication services. As a result, for example, a user of the mobiledevice can be reminded to make a telephone call while the mobile deviceis still within an area in which telephone calls can be made.

For another example, an application executing on a vehicle's navigationsystem that is tethered to a mobile device such as a smart phone canregister to receive notifications about the mobile device's imminententry into a region of poor quality communication services. Thevehicle's navigation system can benefit from such knowledge in order tobecome aware of future times during which the system will not be able touse wireless communication network services to search for gas stationsat which the vehicle can be refueled. In response to receiving anotification that the mobile device will be entering such a regionwithin five minutes and is predicted to remain within that region forthirty minutes, the vehicular navigation system can measure the amountof fuel that the vehicle currently has in its tank, and can proactivelysearch for gas stations along the route or in the regions through whichthe vehicle is predicted to travel during those thirty minutes. Thevehicular navigation system can determine, based on all of thisinformation, whether the vehicle will need to stop at one of these gasstations in order to refuel before the tank becomes empty. The vehicularnavigation system can then notify its user of such a need, and of thelocation of nearby gas stations, in advance of the time that the mobiledevice and the vehicle carrying it enter into the region of poor qualitycommunication services. Thus, by registering for such notifications fromthe mobile device, the vehicular navigation system can avoid beingcaught in a predicament in which the system failed to alert the user ofthe need to refuel because the system was unable to use a wirelesscommunication network to search for the closest gas stations at the timethat the system detected a low fuel level in the vehicle's gas tank.

Adjusting for Network Technology Types

As is discussed above, in an embodiment of the invention, the remoteserver maintains a separate network communication service quality mapfor each different network technology type (e.g., 2G, 3G, 4G, etc.).These maps can indicate the available throughput that is anticipated tobe available for each region within the map; different networktechnology types have different throughput capabilities. In anembodiment of the invention, based on this information, a mobile devicecan determine the average throughput that will be available to itsapplications along its anticipated course or route of travel. In anembodiment of the invention, the mobile device can use this throughputinformation to determine an amount of time, prior to entry into aparticular low quality network communication signal region, which themobile device will need in order to notify registered applications tocommence aggressive data buffering. For example, if the throughputavailable on the mobile device's route is relatively low, then theregistered applications can benefit from receiving pre-cachingadvisories earlier along the route, permitting those applications topre-cache a sufficient quantity of data prior to entering a low qualitynetwork communication signal region.

Embodiments of the present invention can be realized using anycombination of dedicated components and/or programmable processorsand/or other programmable devices. The various processes describedherein can be implemented on the same processor or different processorsin any combination. Where components are described as being configuredto perform certain operations, such configuration can be accomplished,e.g., by designing electronic circuits to perform the operation, byprogramming programmable electronic circuits (such as microprocessors)to perform the operation, or any combination thereof. Further, while theembodiments described above can make reference to specific hardware andsoftware components, those skilled in the art will appreciate thatdifferent combinations of hardware and/or software components can alsobe used and that particular operations described as being implemented inhardware might also be implemented in software or vice versa.

Computer programs incorporating various features of the presentinvention can be encoded and stored on various computer readable storagemedia; suitable media include magnetic disk or tape, optical storagemedia such as compact disk (CD) or DVD (digital versatile disk), flashmemory, and other non-transitory media. Computer readable media encodedwith the program code can be packaged with a compatible electronicdevice, or the program code can be provided separately from electronicdevices (e.g., via Internet download or as a separately packagedcomputer-readable storage medium).

Thus, although the invention has been described with respect to specificembodiments, it will be appreciated that the invention is intended tocover all modifications and equivalents within the scope of thefollowing claims.

What is claimed is:
 1. A method of obtaining relevant wireless networkcommunication signal quality map data, the method comprising: detecting,at a mobile device, that the mobile device is traveling along aparticular path; in response to detecting that the mobile device istraveling along the particular path, determining one or more regions, ofa plurality of regions of a map, that are intersected by the particularpath; wirelessly downloading to the mobile device, from a server, a setof one or more map tiles that correspond to the one or more regions thatare intersected by the particular path; wherein the set of one or moremap tiles: excludes map tiles that do not correspond to the one or moreregions that are intersected by the particular path; and are based atleast in part on measurements that the server received from two or moremobile devices of a plurality of mobile devices, the measurementsindicating qualities of network communication signals within the one ormore regions that are intersected by the particular path; and based onat least in part on the measurements, sending one or more notificationsto one or more applications.
 2. The method of claim 1, wherein detectingthat the mobile device is traveling along the particular path comprises:determining a current location of the mobile device using sensors of themobile device; determining a current direction of travel of the mobiledevice using sensors of the mobile device; determining a current speedof travel of the mobile device using sensors of the mobile device; anddetecting that the mobile device is traveling along the particular pathbased at least in part on the current location, the current direction oftravel, and the current speed of travel.
 3. The method of claim 1,wherein detecting that the mobile device is traveling along theparticular path comprises: automatically determining a route along oneor more map-specified paths from a specified origin to a specifieddestination; and detecting that the mobile device is traveling along theparticular path based at least in part on the automatically-determinedroute.
 4. The method of claim 1, wherein detecting that the mobiledevice is traveling along the particular path comprises: determiningwhether any data stored on the mobile device indicates a route that themobile device will follow in the future; and in response to determiningthat no data stored on the mobile device indicates a route that themobile device will follow in the future, detecting that the mobiledevice is traveling along the particular path based at least in part ona location, a speed, and a direction automatically detected using one ormore sensors of the mobile device.
 5. The method of claim 1, furthercomprising: presenting, on a display of the mobile device, at least aportion of the set of one or more map tiles.
 6. The method of claim 1,further comprising: based at least in part on a quality of servicespecified within the measurements, sending the one or more notificationsto one or more applications that have registered to receive the one ormore notifications.
 7. The method of claim 1, further comprising: basedat least in part on a quality of service specified within themeasurements, sending the one or more notifications to one or moreapplications that have registered with a signal quality mappingapplication to receive the one or more notifications.
 8. The method ofclaim 1, further comprising: based at least in part on a quality ofservice specified within the measurements, sending the one or morenotifications to one or more applications that have registered with anoperating system of the mobile device to receive the one or morenotifications.
 9. A computer-readable storage medium storinginstructions which, when executed by one or more processors, cause theone or more processors to perform: estimating a set of regions, within aplurality of regions on a map, into which a particular device is goingto travel; in response to said estimating, downloading, from a server,to said particular device, information that two or more other devicesmeasured while the two or more other devices were within regions withinthe set of regions, wherein the information that the two or more otherdevices measured indicates qualities of network communication signalswithin the regions within the set of regions; and based at least in parton the information: instructing one or more applications executing onsaid particular device to pre-cache content prior to entry of saidparticular device into a particular region within the set of regions;and sending one or more notifications to one or more applications. 10.The computer-readable storage medium of claim 9, wherein theinstructions, when executed by the one or more processors, further causethe one or more processors to perform: after downloading saidinformation from said server, downloading, from said server, to saidparticular device, information that two or more other devices measuredwhile the two or more other devices were within regions excluded fromthe set of regions.
 11. The computer-readable storage medium of claim 9,wherein the instructions, when executed by the one or more processors,further cause the one or more processors to perform: based at least inpart on a quality of service specified within said information, sendingsaid one or more notifications to one or more applications.
 12. Thecomputer-readable storage medium of claim 9, wherein the instructions,when executed by the one or more processors, further cause the one ormore processors to perform: based at least in part on a quality ofservice specified within said information, instructing the one or moreapplications executing on said particular device to pre-cache contentprior to entry of said particular device into the particular regionwithin the set of regions.
 13. The computer-readable storage medium ofclaim 9, wherein instructing one or more applications executing on saidparticular device comprises instructing the one or more applications topresent at least a portion of the pre-cached content on a display ofsaid particular device.
 14. The computer-readable storage medium ofclaim 9, wherein the instructions, when executed by the one or moreprocessors, further cause the one or more processors to perform: basedat least in part on a quality of service specified within saidinformation, sending said one or more notifications to one or moreapplications that have registered with an operating system of saidparticular device to receive said one or more notifications.
 15. Thecomputer-readable storage medium of claim 9, wherein the instructions,when executed by the one or more processors, further cause the one ormore processors to perform: based at least in part on a quality ofservice specified within said information, sending said one or morenotifications to one or more applications that have registered with asignal quality mapping application to receive said one or morenotifications.
 16. A computer-readable storage medium storinginstructions for obtaining relevant wireless network communicationsignal quality map data, the instructions being executable by one ormore processors to cause the one or more processors to performoperations comprising: detecting, at a mobile device, that the mobiledevice is traveling along a particular path; in response to detectingthat the mobile device is traveling along the particular path,determining one or more regions, of a plurality of regions of a map,that are intersected by the particular path; wirelessly downloading tothe mobile device, from a server, a set of one or more map tiles thatcorrespond to the one or more regions that are intersected by theparticular path; wherein the set of one or more map tiles: excludes maptiles that do not correspond to the one or more regions that areintersected by the particular path; and are based at least in part onmeasurements that the server received from two or more mobile devices ofa plurality of mobile devices, the measurements indicating qualities ofnetwork communication signals within the one or more regions that areintersected by the particular path; and based on at least in part on themeasurements, sending one or more notifications to one or moreapplications.
 17. The computer-readable storage medium of claim 16,wherein detecting that the mobile device is traveling along theparticular path comprises: determining a current location of the mobiledevice using sensors of the mobile device; determining a currentdirection of travel of the mobile device using sensors of the mobiledevice; determining a current speed of travel of the mobile device usingsensors of the mobile device; and detecting that the mobile device istraveling along the particular path based at least in part on thecurrent location, the current direction of travel, and the current speedof travel.
 18. The computer-readable storage medium of claim 16, whereindetecting that the mobile device is traveling along the particular pathcomprises: automatically determining a route along one or moremap-specified paths from a specified origin to a specified destination;and detecting that the mobile device is traveling along the particularpath based at least in part on the automatically-determined route. 19.The computer-readable storage medium of claim 16, wherein detecting thatthe mobile device is traveling along the particular path comprises:determining whether any data stored on the mobile device indicates aroute that the mobile device will follow in the future; and in responseto determining that no data stored on the mobile device indicates aroute that the mobile device will follow in the future, detecting thatthe mobile device is traveling along the particular path based at leastin part on a location, a speed, and a direction automatically detectedusing one or more sensors of the mobile device.
 20. Thecomputer-readable storage medium of claim 16, wherein the set of one ormore map tiles are based at least in part on stored map data thatspecifies, for each particular region of the one or more regions, aquality of a network communication signal within that particular region.21. The computer-readable storage medium of claim 20, wherein: themeasurements comprise a first measurement from a first mobile devicethat used a 3G network when making the first measurement; themeasurements comprise a second measurement from a second mobile devicethat used a 4G network when making the second measurement; the serverupdated the stored map data using the first measurement to update firstmap data that pertains to the 3G network but not to update second mapdata that pertains to the 4G network; and the server updated the storedmap data using the second measurement to update the second map data thatpertains to the 4G network but not to update the first map data thatpertains to the 3G network.
 22. The computer-readable storage medium ofclaim 16, wherein: the measurements comprise a first measurement from afirst mobile device that subscribes to a wireless network of a firstwireless carrier; the measurements comprise a second measurement from asecond mobile device that subscribes to a wireless network of a secondwireless carrier that differs from the first wireless carrier; theserver used the first measurement to update first map data that pertainsto the wireless network of the first wireless carrier but not to updatesecond map data that pertains to the wireless network of the secondwireless carrier, and the server used the second measurement to updatethe second map data that pertains to the wireless network of the secondwireless carrier but not to update the first map data that pertains tothe wireless network of the first wireless carrier.
 23. Thecomputer-readable storage medium of claim 16, wherein the instructions,when executed by the one or more processors, further cause the one ormore processors to perform: presenting, on a display of the mobiledevice, at least a portion of the set of one or more map tiles.
 24. Thecomputer-readable storage medium of claim 16, wherein the instructionsfurther comprise instructions executable by the one or more processorsto cause the one or more processors to perform operations comprising:based at least in part on a quality of service specified within themeasurements, sending the one or more notifications to one or moreapplications that have registered to receive the one or morenotifications.
 25. The computer-readable storage medium of claim 16,wherein the instructions further comprise instructions executable by theone or more processors to cause the one or more processors to performoperations comprising: based at least in part on a quality of servicespecified within the measurements, sending the one or more notificationsto one or more applications that have registered with a signal qualitymapping application to receive the one or more notifications.
 26. Thecomputer-readable storage medium of claim 16, wherein the instructionsfurther comprise instructions executable by the one or more processorsto cause the one or more processors to perform operations comprising:based at least in part on a quality of service specified within themeasurements, sending the one or more notifications to one or moreapplications that have registered with an operating system of the mobiledevice to receive the one or more notifications.
 27. A methodcomprising: estimating a set of regions, within a plurality of regionson a map, into which a particular device is going to travel; in responseto said estimating, downloading, from a server, to said particulardevice, information that two or more other devices measured while thetwo or more other devices were within regions within the set of regions,wherein the information that the two or more other devices measuredindicates qualities of network communication signals within the regionswithin the set of regions; and based at least in part on theinformation, sending one or more notifications to one or moreapplications that have registered with an operating system of saidparticular device to receive the one or more notifications.
 28. Themethod of claim 27, further comprising: after downloading saidinformation from said server, downloading, from said server, to saidparticular device, information that two or more other devices measuredwhile the two or more other devices were within regions excluded fromthe set of regions.
 29. The method of claim 27, further comprising:based at least in part on a quality of service specified within saidinformation, sending the one or more notifications to the one or moreapplications that have registered with the operating system of saidparticular device to receive the one or more notifications.
 30. Themethod of claim 27, further comprising: based at least in part on aquality of service specified within said information, instructing one ormore applications executing on said particular device to pre-cachecontent prior to entry of said particular device into a particularregion within the set of regions.